POS0419 DIFFERENTIAL miRNA EXPRESSION AND ENDOTHELIAL CELL FUNCTION IN RHEUMATOID ARTHRITIS AND PSORIATIC ARTHRITIS
Authors: O. Tynan, C. Cunningham, M. Hanlon, A. Floudas, M. Canavan, U. Fearon, D. Veale
Journal: Annals of the Rheumatic Diseases (2022)

Background Rheumatoid arthritis (RA) and Psoriatic arthritis (PsA) constitute forms of inflammatory arthritis (IA) characterised by enhanced angiogenesis, immune cell infiltration, and generation of a hypoxic microenvironment leading to an invasive synovial pannus that results in bone and cartilage destruction. However, significant differences in circulating biomarkers in addition to disease pathogenesis at the clinical, immunological, cellular, and molecular levels have been identified that differentiate the two pathotypes. Objectives The aim of this study was to examine circulatory miRNA as cellular biomarkers that can distinguish RA form PsA and to evaluate the potential implication for disease pathogenesis. Furthermore, this study aimed to examine the differential effect of the joint microenvironment on endothelial cell (EC) function in both RA and PsA. Methods RA, PsA and healthy controls (HC) were recruited from St. Vincent’s University Hospital, and serum was collected. Multiplex analysis of 68 serum miRNAs was performed using the FirePlex miRNA Immunology-V2 panel (FirePlex Bioworks Inc). Receiver operator characteristic (ROC) curves were generated to determine sensitivity and specificity of specific miRNAs whilst DNA intelligent analysis (DIANA)-mirPath and STRING software were used to analyse pathways targeted by the dysregulated miRNAs. Additionally, human umbilical vein endothelial cells (HUVEC) were cultured with RA and PsA synovial fluid (SF). Angiogenesis, invasion, and cellular adhesion were quantified by Matrigel tube formation assays, wound healing assays, and adhesion assays. Real-time cellular bioenergetics was analysed in HUVEC in response to RA and PsA SF using the Seahorse XFe96 Analyser. Results 7 miRNAs; miR-126-3p, miR-29b-3p, miR-22-3p, miR-223-3p, miR-320a, let-7g-5e, and let-7g-5p (all**p≤0.01), were significantly elevated in RA serum compared to both PsA patients and HC, with ROC curve analysis demonstrating the predictive accuracy with which each miRNA differentiated between RA and PsA (all &lt;0.05). Biplot analysis further identified that three miRNA, miR-29b-3p, miR-22-3p, and miR-223-3p demonstrated the greatest separation between RA and PsA (all p&lt;0.05). DIANA and STRING analysis identified the P13K-Akt pathway as being the primary target of these 3 miRNAs with specific gene targets involved in this pathway including factors all importantly associated with endothelial cell migration, proliferation, invasion, and angiogenesis. Next, we examined the effect of the joint microenvironment on endothelial cell function and demonstrated that PsA SF significantly enhanced EC tube formation (p&lt;0.05) and EC leukocyte adhesion (p&lt;0.05), with RASF only significantly inducing EC leukocyte adhesion. Finally, metabolic analysis of endothelial cells demonstrated that PsA SF significantly induced baseline glycolysis (p&lt;0.05), baseline OCR (p&lt;0.05), maximal respiratory capacity (p&lt;0.05) and spare respiratory capacity (p&lt;0.05), with no effect observed for RA SF. Conclusion Circulating miRNAs may be valuable as diagnostic biomarkers that can distinguish RA from PsA. Additionally, the joint microenvironment induces EC function and metabolic capacity, with these effects more pronounced in response to PsA SF compared to RA SF. References [1]Cunningham, C. C., S. Wade, A. Floudas, C. Orr, T. McGarry, S. Wade, S. Cregan, U. Fearon, and D. J. Veale. 2021. Serum miRNA Signature in Rheumatoid Arthritis and “At-Risk Individuals”. Front Immunol 12. [2]Wade, S. M., T. McGarry, S. C. Wade, U. Fearon, and D. J. Veale. 2020. Serum MicroRNA Signature as a Diagnostic and Therapeutic Marker in Patients with Psoriatic Arthritis. J Rheumatol 47: 1760-1767 [3]Fromm, S., C. C. Cunningham, M. R. Dunne, D. J. Veale, U. Fearon, and S. M. Wade. 2019. Enhanced angiogenic function in response to fibroblasts from psoriatic arthritis synovium compared to rheumatoid arthritis. Arthritis Res Ther 21: 297. Disclosure of Interests None declared.